"Popping" sound
aferretti3
Member Posts: 21 ✭
Hey everybody! I have a 2007 280 EC with the 496 mag mercruiser. This past weekend we started having an issue with the engine....at higher rpm's (3800 and higher) and while trying to get on plane the engine starts making loud "popping" noise. At idle, slow ahead, slow reverse, even at mid range forward the engine is great.?. My brother in law was wondering if I had gotten a bad batch of gas (possible water in the fuel)?.? I had filled up two weeks ago but cruised for a couple hours after filling up. It wasn't until the next week when I took it out again that this noise started. Bad gas, bad spark plugs, ?,?,?. I don't know anything about engines so any advice would be much appreciated!!
Comments
Follow the fuel line to the front of the engine. Does it have a big twist-on fuel filter that looks similar to an oil filter? Take it off and pour the contents into a clear container such as a jar. Wait a minute or two -- does the fuel separate into two layers? If so, replace the fuel filter and that should solve your problem.
Duane, did your issue get fixed?
if you've addressed wires, plugs, dizzy cap, fuel/filters and other obvious culprits, it could be that you're timing is off.
I don't know how these engines advance with a carb- whether it's vacuum or signal from a sensor ( cam shaft or crank sensor), but with a computer (ECM/PCM) it's without doubt a result of the tables on the computer reconciling with the crank position sensor (ckps) and/or cam position sensor (cps).
other sensors that could be impacting fuel trim/timing advance on a computer controlled engine are the MAP/MAF (dunno which you got, one or the other), and the air intake temperature sensor (AIT), either of which give readings to the computer which the computer reconciles and adjusts trim/spark accordingly.
now here's the thing- when the computer is doing it's thing based off of sensor readings, that's called 'closed loop', and it's usually a result of reaching operational temperature and the computer receiving reasonable (reconciled) readings from each of the sensors in the loop... that's the way the thing operates... something else it does, though, is it 'opens' loop at or near WOT- disregarding the messages being sent by the sensors and just tossing max fuel at the engine under a fixed spark advance (likely around -37*tdc)- which is somewhat of a 'protection' in the case fuel runs lean...
no matter if you're using a thunderbolt ignition or a PCM, they record predets... That 'popping' would concern me until I ruled predetonation out as a cause. Get a scanner on those things and see if that's the issue.
If you put the boat in neutral and bring the rpm's up does it make the same sound?
PC BYC, Holland, MI
Dream 'Inn III -- 2008 400 Express
Glad you found your problems and were able to get fixed quickly. I just noticed you too are in Cleveland, what marina are you at? We are at Olde River this year. Also, what mechanic do you use. We are still new to Cleveland, I like to ask around for opinions and thoughts on area mechanics.